Tiny Tach~great little device for testing

[keninaz]

I live at elevation and wanted to test for optimum RPM and prop pitch and it was recommended here that I get a Tiny Tach. I ordered one directly from the manufacturer and it took about 5 minutes to install.
Of note, I was told by them that outboard motors are some of the noisiest motors produced and they recommended the filtered version (same price) of the Tiny Tach.
I tried it out a bit before hitting the water to do my testing and it's solid as a rock, easy to read and I think will be very handy in testing. I checked the service manual for my little 9.9 HP motor and they say that the 4 stroke should be hitting 5700-5800 (spark reduction starts at 5850 and is pre programmed at the factory to protect the motor).
Reading here that each 1" of reduction in pitch will give me an additional 150-200 RPM in a lightly loaded boat and having the tach should take the guesswork out of which prop I need for 5000' and above.

 

[Sea Rider]

A 9.9 engine could be "little" but very capable. assume you have ordered the model that has programmable spark firing sequence ? With healthy engine, well transom seated & trimmed the cast on stone theory does not appy to light or mediumweight boats, expect to achieve + 400-500 rpm while lighty loaded, solo driving with just one less prop pitch reduction. Probably can obtain 150-200 + rpm at high elevation due to engine's notorious power loss, a matter to test and see what happens.

You will reach a point that won't be able to find a spot on prop pitch to pull your rpm to max 5800, at elevation it's a carb rejet - less pitch combination, not just plain prop swap.

Happy Boating

 

[keninaz]

Yes, I am afraid of that, but I will try to get as much as I can out of it without jetting. On this model you must remove and disassemble the carb to change the jets and most of my fishing will be right around the 5000-5500 elevation
I am limited to 10 HP on many of the lakes up here.
I also have an electric trolling motor and I may find that it will work better for me even if I have to have dual batteries.
If that happens I will leave the motor stock and use it on occasion when I take it to a lower elevation on the bigger lakes so I don't wear my battery out getting to where I want to go.